REGULARITIES OF HYDROGEN REMOVAL ON THE LADLE DEGASSING PLANT

 The article describes the analysis of degassing technology of 09G2S steel, smelted in an electric arc furnace and processed in the ladle furnace in the conditions of EAF JSC “Ural Steel”. The main parameters of steel degassing have been identified. These parameters, determining the hydrogen removal efficiency on the degassing unit of chamber type, are: level and period of steel degassing, argon consumption, metal temperature, thickness of the slag layer and the value of free board. It was found that the most significant impact on the hydrogen content can be observed at increasing the duration of deep steel degassing up to 20 minutes. Further increase in treatment time is not advisable. The greatest effect of the residual pressure during degassing was observed while reducing the minimum pressure to 2 mbar. The results of steel degassing worsen significantly at the increasing of the residual pressure. Increasing metal temperature up to 1600 - 1620°C promotes the removal of hydrogen, but at temperatures above 1620°C substantially slows the hydrogen removal. The quantitative impact of steel degassing parameters and the regression equation were found and that allows to predict the results of the hydrogen removal. This equation allows to determine the steel degassing parameters and to achieve a predetermined content of hydrogen in steel. The rational parameters of steel degassing were determined, which provide of hydrogen content to 2.1 ppm in the steel: a superheat temperature of metal - 100-110°C, the duration of the steel degassing process to 20 minutes under the pressure in the vacuum vessel at most 1.5 mbar, argon consumption - 0.05 m³/t. The losses of metal temperature are determined by the total duration of the processing, which depends on the duration of deep vacuum, on the technical capabilities of equipment and organization of the degassing steel process. The minimum residual content of hydrogen in steel, which is 1.6 ppm, is ensured at carrying out of steel degassing with superheat temperature of 120 - 125°C for 40 minutes at a pressure in the vacuum vessel at most 1 mbar and with the consumption of argon – to 0.072 m³/t.

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